John Deere zero turn mower with Briggs engine troubles

jstubbs · #1 06-11-2020, 08:38 PM

Hi AO, in lieu of anyone better to ask at the moment, want to see if anyone can help me figure out WTF is going on with this cursed mower. Please don't mind the giant wall of text lol, may as well give all the details

It's a 2014 John Deere Z225 zero turn mower with the 18.5 Briggs & Stratton engine. We bought it off a family friend who almost never used it, when it came into our possession last summer it had less than 30 hours on it, and only has 38 hours on it now.

Anyway, worked great for the first bunch of times mowing 8 or so hours of use. Then one day I go to fire it up and it won't start, just kept turning over. Cranked it for about 30 or so seconds wondering WTF till I notice gas coming out of the damn tail pipe. Great.

Changed the plug, changed the oil with fresh oil and new filter, and took the carb off and cleaned it out. Wasn't dirty at all inside, in fact looked like new, no green buildup or anything. Threw it all back together and still wouldn't start. Had two buddies over, both very mechanically inclined, and then tried cleaning every little crevice of the carb possible, and still wouldn't start. Fuel was getting to the bowl so we figured the fuel pump must be fine. Finally we tried squirting a bit of gas straight through the intake, and it would fire up and run but only until you stopped forcing gas through.

Took it to my local Deere dealer, they diagnosed it as needing a new carb. They installed a brand new carb and it worked good. It ran great when I picked it up, drove it on the trailer and took it home. Next day go to drive it off the trailer and it won't start. Take it back to the dealer, and the damn fuel tank fell off at some point driving it back to Deerline (had the shroud cover off, which holds the fuel tank, off the unit), totally my idiotic fault. A new fuel tank was $300 and I was pretty ****ed off at this point plus money was getting a bit tight so I just left it sitting in my garage till spring.

Spring arrives, I order in a new tank, it arrives, I install it, and it fires up no problem. Checked the oil, level seemed pretty high, so I drained a bit out, thought the oil looked a bit thin but figured it must be my imagination since I just put fresh oil in and it's been ran less than 5 minutes total since Deerline put the new carb on. Decided to mow a test patch of my lawn, it's running flawlessly, then it backfires a bunch of blue smoke. I shut it off, check the oil, the level is high again and oil looks even thinner now. Seemed to smell a bit like gas. Fired it up again just to drive it off my lawn and onto the driveway so I could pull it into the garage, and it's smoking a bit the whole way.

What do you guys figure? Carb still flooding gas into the crankcase somehow and that diluted the oil and that hurt the engine?

sweld · #2 06-11-2020, 09:15 PM

Throttle linkage.

Sent from my iPhone using Tapatalk

EZM · #3 06-11-2020, 09:57 PM

https://www.briggsandstratton.com/na...il-issues.html

maybe something on this website .....

1886 · #4 06-11-2020, 11:09 PM

Vacuum operated fuel pumps can leak gas into the crank case. Check the fuel pump as it could be the problem.

Drewski Canuck · #5 06-11-2020, 11:39 PM

Obviously has a spark, so torn diaphragm in the fuel pump or your bowl needle is not closing from the float, and you are flooding out to the point of gas being drawn into the crank but that seems like it would hydro lock first????

So take off the bowl nut, look at the carb float to be sure, then see if you can take off the fuel pump and see if it has a torn diaphragm.

If you have a spare tank anyways, just try and run some gas by gravity to the carb on a bypass of the pump. If that works, then it is the pump.

Just put a 19 hp professional series B & S engine on my riding mower to replace the old consumer grade B & S engine on a Ariens lawn tractor. Did notice that the professional series had a fuel pump where the old one was gravity only.

Drewski

Big Grey Wolf · #6 06-12-2020, 07:52 AM

B & S engine needs proper valve settings to start. Pull valve cover and believe .005 in. on intake and .007 exhaust. Will just crank around like Ford truck if valves off.

dfarms11 · #7 07-09-2020, 08:04 AM

my 435 just did this. It was my fuel pump leaking fuel into the crank

Dean2 · #8 07-09-2020, 08:33 AM

Wonder if the OP ever got it figured out as the original post was over a month ago. Would be interesting to hear the outcomes of these posts and see if the online diagnostics were right.

bagwan · #9 07-09-2020, 12:27 PM

I had a problem last year with a Cub Cadet 20 hp Kohler that was hard to start since new and finally quit. They have a solenoid shut off valve that cuts the gas off when shutting down the engine. This one shut off the fuel completely. New one was more than the carb price so I removed the solenoid guts and installed a shut off valve in the line to the carb. Cost $7 vice 150 and works like a charm as long as I remember to open valve. Just an info for anyone else having the same problem. Solenoid worked off the ignition switch.

Armorman · #10 07-10-2020, 06:55 AM

Ya, I'd like to know too. I'm having the exact same problem with a Z665. I think mine has a 25 HP Briggs tho. Interesting to hear that there are 3 of us in this thread with the exact same problem but with 3 different models.

Sent from my Pixel 3 XL using Tapatalk

jstubbs · #11 07-10-2020, 03:05 PM

Quote:

Originally Posted by Dean2

Wonder if the OP ever got it figured out as the original post was over a month ago. Would be interesting to hear the outcomes of these posts and see if the online diagnostics were right.

It is at a trusted small engine repair shop right now but they said they won't have a chance to look at it for probably another week+. Took me awhile to get it there, been busy as hell.

Soon as I know the issue, I will provide an update.

sourdough doug · #12 07-10-2020, 11:41 PM

If the fuel pumps seem to be the problem, I am wondering if the components of these pumps are being compromised by the use of our ethanol fuels. I like to blame ethanol. Have seen what it does to other components...??

wildwoods · #13 07-10-2020, 11:51 PM

Briggs and Scrap-iron
Ask me how I know

Reeves1 · #14 07-11-2020, 04:44 AM

I had problems sort of the same with my JD ride on (22 HP?) and it turned out to be the vent hole in the top of the gas cap was plugged.

jstubbs · #15 08-10-2020, 10:57 AM

Turns out the valves were totally out of spec, to the point it even bent a pushrod. Given the extremely low hourage they figured it was that way from factory. The shop set the valves and replaced the bent push rod and so far seems good.

Shout out to Alberta Small Engine Repair on 50th st in Edmonton. Great work and very reasonable. For that work and also new plug, filters and oil change the total wasn’t even $500.

Dean2 · #16 08-10-2020, 11:09 AM

Quote:

Originally Posted by jstubbs

Turns out the valves were totally out of spec, to the point it even bent a pushrod. Given the extremely low hourage they figured it was that way from factory. The shop set the valves and replaced the bent push rod and so far seems good.

Shout out to Alberta Small Engine Repair on 50th st in Edmonton. Great work and very reasonable. For that work and also new plug, filters and oil change the total wasn’t even $500.

Glad you got it figured out and fixed. That said, your version of reasonable and mine are quite different. Oil change, air and oil filter plus a plug should have been no more than $70, they only hold 1-2 litres. So $430 to replace a push rod and adjust the valves is really steep. At $100 an hour that is 4 hours for what is a 1-2 hour job. I had a valve adjust and timing belt, water pump and tensioners replaced on a V8 Lexus for $950 including $240 for the parts. That is a lot more work that a single lunger Briggs and Straton.

Bergerboy · #17 08-10-2020, 12:01 PM

Quote:

Originally Posted by Dean2

Glad you got it figured out and fixed. That said, your version of reasonable and mine are quite different. Oil change, air and oil filter plus a plug should have been no more than $70, they only hold 1-2 litres. So $430 to replace a push rod and adjust the valves is really steep. At $100 an hour that is 4 hours for what is a 1-2 hour job. I had a valve adjust and timing belt, water pump and tensioners replaced on a V8 Lexus for $950 including $240 for the parts. That is a lot more work that a single lunger Briggs and Straton.

If this is a common problem that price would be out of line. If they did a couple hours of trouble shooting other possible causes it is justified as someone has to pick up the bill for shop time. They probably went through the fuel system to confirm its integrity as that is the most likely cause. Improperly set valves resulting in a bent push rod with such low hours is a strange one.

jstubbs · #18 08-10-2020, 12:06 PM

Quote:

Originally Posted by Dean2

Glad you got it figured out and fixed. That said, your version of reasonable and mine are quite different. Oil change, air and oil filter plus a plug should have been no more than $70, they only hold 1-2 litres. So $430 to replace a push rod and adjust the valves is really steep. At $100 an hour that is 4 hours for what is a 1-2 hour job. I had a valve adjust and timing belt, water pump and tensioners replaced on a V8 Lexus for $950 including $240 for the parts. That is a lot more work that a single lunger Briggs and Straton.

You are likely right, mostly I was just really relieved that it didn’t need a new engine. Lol

Dean2 · #19 08-10-2020, 12:10 PM

Quote:

Originally Posted by Bergerboy

If this is a common problem that price would be out of line. If they did a couple hours of trouble shooting other possible causes it is justified as someone has to pick up the bill for shop time. They probably went through the fuel system to confirm its integrity as that is the most likely cause. Improperly set valves resulting in a bent push rod with such low hours is a strange one.

Fair comment but diagnosis by someone who does this for a living is, pull and ground plug, is there spark, yes then reinstall, squirt gas in carb throat, does engine start and run, if yes, chase down fuel problem, if no, compression test. Compression test would have spotted the valve issue right away. Elapsed time 15-20 minutes.